Vibrating apparatus for concrete



Nov. 1, 1955 J. BAKKER VIBRATING APPARA'I JTL IS FOR CONCRETE FiledMarch 50, 1953 FIG United States Patent VIBRATING APPARATUS FOR CONCRETEJohannes Bakker, Lange Ruige Weide, Netherlands Application March 30,1953, Serial No. 345,486

2 Claims. (Cl. 259-72) The invention relates to a vibrating apparatus,more particularly a vibrating table, for vibrating concrete or likeplastic hardening material, in which the vibrating surface isresiliently connected to a supporting frame and the oscillations aregenerated by means of rotatable eccentric masses.

Such apparatus are known. They have a single vibrating surface in theform of a table-leaf or a vibrating frame composed of longitudinal andtransverse girders, which vibrating surface at the bottom side carries aspindle extending over a. part of the length in the middle thereof andprovided with mutually in phase eccentric masses, which spindle isdriven by a motor. Though in this way the drawback of vibratingapparatus with a relatively large vibrating surface which is brought tovibration by a single eccentric mass, that the intensity of thevibrations decreases with the distance from the source of oscillations,can be met, these known constructions have the drawback, that the longspindle and the bearings are very unfavourably loaded, as well as themotor. For meeting this drawback it is also known to arrange theeccentric masses each on a short spindle supported in hearings on bothsides, which spindles are mutually connected by flexible couplings, sothat all eccentric masses can be driven in common and mutually in phase.In this way, indeed, in mechanical respect an improvement is obtained,but the unfavourable load remains and is even still more unfavourablethan with vibrating apparatus with a single source of oscillations asthe more uniform distribution of the intensity of vibration over thearea of the vibrating surface is obtained by a considerable increase ofthe total excentric mass. With all these vibrating apparatus,furthermore, the number of oscillations generally does not surpass about3000 oscillations/ min. Indeed, vibrating apparatus are known in whichvery fast running motors are used, which attain up to 8000-9000oscillations/min, but these latter apparatus can only be made forlimited small powers. It is, however, known that for vibrating concretefor several reasons higher numbers of oscillations would be verydesirable.

The invention now aims at providing a vibrating apparatus with whichvery high numbers of oscillations of selected powers and very favorabledistribution of the intensity of vibration over the vibrating surfacecan be obtained.

According to the invention this is achieved by that the vibratingsurface is composed of a number of separate parts lying beside oneanother, which parts can each be brought to oscillation by a rotatableexcentric mass, the excentric masses being mutually coupled out of phasein such a manner that they jointly transmit a multiple of the frequencyof oscillation of each of the masses to the material to be vibrated. Inthis way a vibrating apparatus is obtained, in which, as the separateparts can be made as narrow rigid beams or girders, a very favourabledistribution of the intensity of oscillation over these parts isobtained, while at the same time with normal 2,722,407 Patented Nov. 1,1955 numbers of revolutions of the driving of the excentric masses ofabout 3000 revolutions/min., by arranging an adequate number of partsbeside one another, easily frequencies of oscillation can be obtained of12000-24000 oscillations/min. and higher, while, by that the number ofrevolutions of the driving does not need to be correspondingly higherbut is a normal number of revolutions of a motor of about 3000revolutions/min, each desired power can be applied. A particularadvantage of the vibrating apparatus according to the invention furtheris, that the number of oscillations of the whole apparatus is no longerdependent of the dimensions of the vibrating surface, as was the case e.g. with the vibrating tables hitherto known, or any way is influenced byit to a considerably smaller degree, as according to the invention nolonger a whole surface is brought to oscillation in which eventuallystationery waves can arise so that no uniform oscillation isobtained-but the vibrating surface is composed of separate oscillatingparts.

Appropriately in practice the rotatable excentric masses are mutuallyadjustable with respect of their phase relation and are unrotatablycoupled by flexible connections and driven in common. Such aconstruction is at the same time favourable for the driving motor as theexcentricities, which are mutually coupled out of phase, act less as anexcentric load as the number of excentricities increases.

The invention will now be further elucidated with reference to anexample of performance shown in the drawing. In the drawing:

Fig. 1 shows an end elevation, partially a cross-section of fourvibrating surface parts resiliently supported beside one another on asupporting frame of a vibrating table according to the invention,

Fig. 2 shows a cross-section, of Fig. 1, and

Fig. 3 shows a partial side elevation of a vibrating surface part withresilient supporting means and excentric mass connected to it.

In the drawing the reference numerals 1, 2, 3, 4 indicate four'vibratingsurface parts of a vibrating table arranged at regular small mutualdistances beside one another. These parts consist of I-girders which areconnected to the supporting frame 8 in a vertically displaceable mannerwith the aid of bolts 5 and upper springs 6 and under springs 7. At oneor both ends the I-girders 14 each carry an excentric mass 11 rotatablyfixed on a spindle 10 which is journalled in a closed housing 9. Theseexcentric masses are secured to the Igirders with the aid of strips 12connected to the housing 9 and bolts 13. The spindles 10 of theexcentric masses are mutu ally connected by flexible couplings 14. Theexcentric masses are fixed to the driven spindles 10 in out of phaserelation and are combined to one or more groups of e. g. four to eightin such a manner that they jointly give, when driven at a speed of about3000 revolutions/min, a frequency of oscillation of the vibratingsurface of 12,000-24,000 oscillations/min. or higher. With a subdivisionof the vibrating surface parts in groups of four I-girders, this e. g.can be obtained by adjusting the excentric masses of the girders 1 and 3mutually 180 out of phase, and likewise the excentric masses of thegirders 2 and 4, but taking care thereof that these latter lie out ofphase with respect of the excentric masses of the girders 1 and 3. Theexcentric masses then all lie mutually 90 out of phase. Thus it is alsopossible to compose groups of five vibrating surface parts with a mutualphase difference of 72, etc. The groups are naturally coupled with oneanother in such a manner that they lie mutually in phase.

An apparatus according to the invention can also be executed as a mouldvibrator and as an immersion vipartially a top elevation alsobe'fixe'din the middle at the "bottom side of the I-girders. A like arrangementof the oscillating masses canalsotbeapplied with other vibrators if.desired.

Having .now 7 particularlydescribed and ascertained .thenaturetofmytsaid'invention an'd'in What manner the ,same is tobelperforme'dll declare that whatlclaim isz 1. ,A vibrating device forvibrating concrete and like plastic hardening material 4 comprising, .incombination, @a supporting 'frame, ,a plurality of spaced, .but closely.adjacent, supporting members providing a supporting surfacerfor thematerial to'be vibrated, :said members being resiliently connected tosaid supporting frame, .and an eccentric mass rotatably mounted in eachofsaid ,members, the eccentric rotatable masses of .said members beingmutuallycoupled out of phase in such manner .that theyjointly transmitto the materialcarriediby said members a multiplesof the frequency ofoscillationof-reachof the masses.

2. A vibrating apparatus as defined in claim 1, wherein each "rotatableeccentric mass is adjustable 'tovaryits phase relation with the othereccentric masses and the eccentric masses are coupled by flexibleconnections and driven simultaneously from a common power source.

References Cited in the file of this patent UNITED STATES PATENTS1,806,620 Flam May 26, 1931 1,943,076 Jackson Jan. 9, 1 934 2,204,007Baily June 11, 1940 2,610,040 Emmons :Sept.*9, 1952 (FOREIGN EPAEEENTrS819,492 France Oct. 19, 1937

